This presentation discusses the current status of our knowledge on radiation issues related to medical imaging.

1. Medical Imaging and Radiation
Dr. Bhavin Jankharia
Jankharia Imaging

2. There is no evidence that low-level
radiation from medical imaging
causes harm
1. Amis Stephen. Radiology 2011: 261: 5
2. Position Statement of the Health Physics Society
3. American Association of Physicists in Medicine – position statement. Dec 2011
4. Hendee William R. Radiology 2012: 264: 312

3. What is the Issue?

4. Radiation in high doses, as with
accidents, nuclear bombs and with
radiotherapy causes damage

5. The doses in such cases are
upwards of 100 mSV and often
much more

6. This damage can be non-stochastic
(skin burns, exfoliation, loss of
hair, diarrhea, etc), which is dose
related….

7. …or stochastic, which are random
events and include DNA
mutations, etc. that can lead to
cancer

8. Medical Imaging
Modalities
•X-Ray
•Computed Tomography
•Mammography
•Nuclear Medicine incl PET/CT

9. Radiation Numbers
Normal
•Normal background - 3 mSv / year (chest x-ray
is 0.1 mSv and chest CT scan is 5-7 mSv).
•The average per person radiation in the US
because of medical imaging has now gone up to
around 6 mSv / year, much less in India.

10. Radiation Numbers
Normal
•Essentially, normally any person will receive up
to 50 mSv of radiation in the first 17 years and
then up to 250 mSv till age 80.

11. Below 50-100 mSv of exposure, the
risks of health effects are either too
small to be observed or non-existent
Position Statement of the Health Physics Society

12. Risks of medical imaging at patient doses below 50
mSV for single procedures or 100 mSv for multiple
procedures over short time periods are too low to be
detectable and may be nonexistent.
Position Statement of the American Association of
Physicists in Medicine, Dec 2011

13. So, what is all the fuss about?

14. The BEIR VII Report
www.nap.edu

15. Based on Japanese bomb survivor
data, risks have been extrapolated

16. Radiation Numbers
Risk
•0.7 to 2.0 % of all cancers are supposed to be
due to low level radiation

17. These extrapolations have often led to
sensationalistic reports in the media

18. Based on the CT scans done in 2007, the National
Cancer Institute projects 29,000 excess cancers…
http://www.npr.org/templates/story/story.php?storyId=121436092

19. In perspective...
http://www.npr.org/templates/story/story.php?storyId=121436092

20. The total number of new cancers per year is
around 1.6 million in the US. The lifetime risk
of getting any kind of cancer is 1 in 2 to 1 in 3
http://www.cancer.org/acs/groups/content/@epidemiologysurveilance/documents/document/
acspc-031941.pdf

21. So unfortunately, this often causes more
harm than good because some patients
and guardians refuse life-saving or
required medical imaging procedures
based on these media reports

22. One New Twist…

23. Radiation Risk
Retrospective Study
•180,000 patients underwent 280,000 CT scans below
22 years of age
•The estimate is that one head CT scan performed in
the first decade of life would produce one excess case
of brain tumor and one excess case of leukemia per
10,000 patients who underwent CT scan, in the first
decade after exposure
Pearce M et al. Lancet. Published online, June 7, 2012

24. It is known that children are particularly more
susceptible to radiation and there is no question
that the radiation dose used should be as low as
possible. The risk however is small and as long
as the study is justified, not really relevant.

25. And while the study’s data and conclusions
have not been particularly challenged, in
the end, this is a retrospective study. What
is required are prospective studies that
address this issue.

26. Age Matters

27. What do you tell a 60 years old man
concerned with the ill-effects of radiation?

28. Radiation Numbers
Risk
•0.7 to 2.0 % of all cancers are supposed to be
due to low level radiation
•In the elderly the risk of cancer from radiation is
less than 0.04%

29. Cumulative Dose and Multiple Tests

30. Two 35 years old men with suspected acute
appendicitis need CT scans. One is a radiation
virgin, the other has had 20 CT abdomen pelvis
studies for treated testicular cancer in the last
10 years with a cumulative dose of 180 mSv
Eisenberg et al. Radiology 2012; 263: 626

31. Radiation Risk
Sunk Cost Effect and Cumulative Dose Issues
•The risk from radiation is stochastic and hence is
a one-time risk related to that particular test.
•Cumulative dose is irrelevant.
•The risk therefore for both patients is the same.
Eisenberg et al. Radiology 2012; 263: 626

32. But, going with the assumption that we
should use radiation wisely…

33. ...the radiology community has taken
significant steps to reduce radiation...

34. ...on the principles of…

35. ALARA (Keeping Radiation Dose As
Low As Reasonably Achievable)

36. ASARA (Keeping Medical Procedures
as Safe as Reasonably Achievable)

37. AHARA (Keeping Medical Benefits as
High as Reasonably Achievable)

38. Radiation Control
Stakeholders
•Vendors
•Radiologists and other health workers
•Regulatory authorities

39. Radiation Control
Vendors
•Radiation reduction technology
•Protocols that use less radiation

40. Radiation Control
Radiologists and other health workers
•Optimal use of investigations
•Using non x-ray based techniques wherever
feasible
•Using protocols with the lowest radiation
possible that still allows accurate diagnosis

41. Radiation Control
Regulatory Authorities
•Monitoring proper use
•Accrediting only appropriate personnel

42. Image Gently
www.imagegently.org

43. Step Lightly

44. Conclusion
Summary
•There is increasing exposure to low level radiation
from medical imaging
•While there is little hard evidence that this is harmful
to people, there is concern based on extrapolated
data from Japanese bomb explosion survivors
•All stakeholders are working hard to reduce radiation
exposure

45. Thank You